Load balancing with APACHE web server

This article provides steps that are needed to configure load balancer while setting up a clustered environment in a distributed network. However, this should not be considered a full and final configuration for a full-fledged production stable configuration. To make a production stable load balancing server, several configurations need to be done.

This is just an illustration of how the basic configuration can be carried out with limited resource availability.

Assumption

• Server 1: Exposed a web service or open for web requests.
• Server 2: Expose a web service that is open for web request and also hosts a apache load balancer
• Server 1 and 2 are running on a separate IPs
• HTTP Port on Server 1: 8091
• HTTP Port on Server 2: 8091
• Apache HTTPD server port: 8090 setup on Server 2

Prerequisites

• Server 1 setup for hosting SOAP service exposed on mule server with following
  URI: http://<>:8091/hello?wsdl
• Server 2 setup for hosting SOAP service exposed on mule server with following
  URI: 
  http://<>:8091/hello?wsdl
• Apache httpd server configured on Server 2

Sequence of operation

• Create and run web service on Server 1
• Create and run web service on Server 2
• Install and configure HTTPD Server as LB instance
  • Configure httpd-proxy-balance.conf
  • Configure httpd.conf
• Assert LB activity

Detailed Steps to setup LB

Create and run web service on Server 1(in this case it is on 10.0.1.43)

• Create a soap based mule web service as shown in the “Message Flow” diagram given below
  
  

• Following is the XML Configuration fie (Watch out that the service is exposed over 10.0.1.43)

    <flow name="soap-web-serviceFlow1" doc:name="soap-web-serviceFlow1">
        <http:inbound-endpoint address="http://localhost:8091/hello"
            exchange-pattern="request-response" doc:name="HTTP">
            <cxf:jaxws-service serviceClass="org.example.HelloWorld" />
        </http:inbound-endpoint>
        <component class="org.example.HelloWorldImpl" doc:name="Java" />
    </flow>

• Run the service with following configuration
  
  

• Add following run time parameter at VM arguments -Dmule.tcp.bindlocalhosttoalllocalinterfaces=true, this should look like
  
  

• With this, the service will be exposed http://10.0.1.43:8091/hello?wsdl

Create and run another web service on Server 2 (in this case it on 10.0.1.86)

•  Repeat the same steps similar to the ones done on Server 1
• Finally the exposed web service should have a URI, http://10.0.1.86:8091/hello?wsdl

Now that we have 2 services running on 2 different servers, configuration of LB for these servers can be done.

Install and configure HTTPD Server as LB instance

• Download and install apache httpd server. (If already exists, then skip to next step). This can be downloaded from http://httpd.apache.org/download.cgi
• Configure httpd-proxy-balance.conf
  • Required to keep this file under ‘conf/extra/’ folder
  • httpd-proxy-balance.conf should look like

<IfModule mod_proxy_balancer.c>
ServerName www.mycompany.com
ProxyRequests off
<Location /balancer-manager>
Set Handler balancer-manager
Order deny,allow
Allow from all
</Location>
ProxyPass /balancer-manager !
ProxyPass / balancer://mycluster/ stickysession=SESSION_ID
<Proxy balancer://mycluster >
BalancerMember http://10.0.1.86:8091 loadfactor=4 route=node1
BalancerMember http://10.0.1.43:8091 loadfactor=6 route=node2
# Load Balancer Settings
# We will be configuring a simple Round
# Robin style load balancer. This means
# that all webheads take an equal share of
# of the load.
ProxySet lbmethod=byrequest
</Proxy>
</IfModule>

• Configure httpd.conf
• Make sure they are uncommented following modules

LoadModule lbmethod_byrequests_module modules/mod_lbmethod_byrequests.so
LoadModule log_config_module modules/mod_log_config.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule slotmem_shm_module modules/mod_slotmem_shm.so
LoadModule proxy_module modules/mod_proxy.so

• Add this line

Include conf/extra/httpd-proxy-balancer.conf

• Save and restart, httpd

Assert LB activity

• Point at the browser, and access http://<>:8090/ In this case it is http://10.0.1.86:8090/hello?wsdl
• This will take us to the exposed web service on a round robin basis and shares equal load between 10.0.1.43 and 10.0.1.86